Hydrocarbon thiophosphoric acid salts of thialdine and certain homologues



2,4,6-trimethyl-1,3,5-dithiazine,

Patented Sept. 9, 11952 1 2,610,182. ,1 V HYDROCARBON THIOPHOSPHORIC ACID SALTS OF THIALDINE AND HOMOLOGUES CERTAIN John P. McDermott, Roselle, N. J., assigiiortd e Standard Oil Development Company, a corporation of Delaware 1 Na Drawing. Application June 22, 1949,

. SerialNo. 100,741

1 fiClairns. (01. 260-243) .f The present; invention relates to ,an improved class of additives #particularly suitable for use in lubricating oils and to the, compounded min eral oils and 1 other hydrocarbon products 1 in which they are employed. r

' Modern developments in the design of internal combustion engines, with increasing engine speeds and compression ratios, have imposed a severe strain on1 the lubricants employed. In particular, the crankcase oil .is raised; to a high temperature and in the course ofits circulation through-the engine is repeatedly exposedhto air under conditions highly. conducive to destructive oxidation. Oxidative breakdown of the oil results in the formation of acidic products which corrode bearing surfaces and do considerable harm to the engine generally. Furthermore, the metallic corrosion products have the effect of catalyzing further oxidative breakdown of the oil.

A number of compounds, more especially those of the phenolic type, are knownwhich exert an oxidation inhibiting effect when added to mineral lubricating oils and other hydrocarbon products. Their effect is-to prevent oxidative breakdown of the oil both on storage (long potential reaction time and low. temperature), and in It is readily prepared by treating the condensa tion product of acetaldehyde and ammonia with hydrogen sulfide. Thialdine and the homologs of the same which are useful for the purposes of the present invention may be represented by the general formula which R is methyl is preferred.

use (short reaction time and high temperature).

Although many antioxidants arcknown. which stabilize the oil adequately on storage, the majority of them tend to breakdown with undesirable rapidity at high-engine operating temperatures.

' A principal object of the present invention is to provide a new class of lubricating oil antioxidants of good properties. Another object is to provide 1 an antioxidant which is stable and effective at relatively high engine temperatures.

Other objects and advantages will be apparent from the following description.

It has now been found, according to the present inventiomthatthe salts formed by reacting thialdine or'fits homologs with carboxylic and thiocarboxylic acids andjthethio acids of phosphorus are extremely effective antioxidants for hydro carbon products liable'to oxidation, especially mineral lubricating oils. v H

Thialdine, otherwise known as 5,6-dihydrothe structural formula is represented by Acids which may be used in fdrmingjthe thi aldine salts of the present invention" include monoor dicarboxylicaliphatic acidswhich may be represented by the general formulas; RGQQH OI l T 00031, where' R represents an aliphatic or sulfuriaed. aliphatic hydrocarbon radical having from ,1 to 30carbon atoms. lhe radical Rfmay be saturated or unsaturated, straight orbranched chain, with orwithout cycloaliphatic substituent chains, or it may be analkyl substituted cyclealiphatic nucleus. Examples fof ,suitable acids are the lower monoanddicarboxylic acids such as butyric, adipic, sebacic, and decanoic acids, Higher acids include lauric, oleic, lino1eic, IiOiIl-r oleic, palmitic, and stearic acids. Mixtures of acids, such as those obtained 'by the oxidation of parafiin wax or other high molecular weight petroleum fractions, may also be used, S'ulfurized acids, in which the sulfur is in the hydrocarbon pared by heating the acid with elemental sulfur or with a sulfur halide. Examples are sulfurized oleic, sulfurized linoleic, and sulfurized-oxidized wax acids. Thio acids of the formula RCOSH, or

, radical, are particularly desirable and may be pre;

xanthic acids of the formula ROCSSH, where R has the same significance as above,jmay also be used. The most preferred products, however, are thoseprepared from the thio acids of; QhQS:

. phorus, such as thiophosphorous and thiosphoric u acids, both from the point of View of effectiveness and fromthepoint of view of ease of prepara tion. In general, partially esterified thiophose phates' or thiophosphites ;are usedto give the monoor di-thialdine salt. These partially esteri:

This product may then be reacted with one mol of thialdine to give an addition" product or "salt.

The compound R"OH may be an alcohol, such as a C2 to C aliphatic straight or branched chain or cyclic alcohol with or without substituent groups such as halogen, sulfur, amino, or nitro groups, or may be a phenol or an alkylated phenol, a'hydroxy ester, hydroxy ether, etc. In general, the total'Tnumber "of carbon atoms in the group .R" sh0u1d"be from 2 to and the num "rofaliphati'c carbon atoms may be from 2 tof24. fEXamples of suitable. compounds are isoprbpyr al'cohol, isobutyl alcohol," 2'-ethylhexanol, iso octyl'alcohol, Cs Oxo alcohols, decyl' alcohol, Lorol (Cm-Cm) alcohols, methylcyclohexyl alcohol, isopropyl. cyclohexyl alcohol, mixed alcohols derived from paraffin wax or from chlorinated parafiin wax, phenol, p-cresol, 2,4,6-triisobutylphenol, p-isooctylphenol, p tert. octylphenol-i p tert octylphenol sulfide; bu-tyl lactate;

d hydroiy butyl-stearate, the various glycolethers khownas' elloso'lves,- such as themonobutyl etheriof ethylene glycol, etc. I

The thiamine-and homologous salts of the pres-- en invention may loe readily formed 'by-"contac thethialdine compound-with the acid atfroom temperature.-- Since heat" is evolved,- the 30 minutes to a solution of 40.8 grams (0.25 mol) of thialdine in 300 cc. of CHC13, maintaining the temperature below .C'. After'stirring for an additionallhour at roomtemperature, the product was filtered and placed on a steam bath was obtained, which upon analysis was found [to c'ontain5.5% phosphorus, 22.1% sulfur, and

2.4 nit'r'ogen.

Example 2 ..-Preparation of thialdine 'methylcyclohezcyl thiophosphate pared by the method described in Example 1,

.usingll grams (1 mol) of methylcyclohexanol and 55.5 grams (0.25 mol) of P2S5.

' pared by the"; method described in-Exahipl The thialdine salt was also prepared by the method described in Example 1, using 96.6 grams (0.3- mon er inet yley mnexyl tincpncspnogm acid and 49.0 grams-'=-(0.3 mol)- cf thialdi-n brown-tacky solidwas obtained iwhich p analysis was found to contain:swapnospmrus, 24.5% sulfur, and 2.1%' nitrogen. 'E m ze 3. r e rctz oa b th azdz negcz criiaq I ;oleyl thiophosphate; '3, ;Sulfurized-oleylthiophosphor-icacid was pre- 11 using" 120*grams -(0. 4m'ol-)i ofsuifuri ed oieyl alcohol (prepared by heating' 'equimcl'ar quan tities of oleyl alcohol and sulfur for ehour at 7 165 c. and 22.2 grams "(oi-mon cf-r gst.

The thia-ldine salt was prepared as described sticky solid'was obtained -which upon-=analy-' reaction-is preferably conducted in the'pr'esence was lieaited -atll'fl C.- for- 45 minutesfwith rapid stirring a l -liter; '3-necked flask "equipped with -a stir-rer therfi10meter and "refit 1X cbndhs e'r. The. resultant acid as then filtered" and blownwith' nitrogen for 10 'minutes.

product. mdnyi thiophospho'ric; acm- 1 mo es; oreach 'was" sadea faropwise over a-"pei'iod m:

sulfur, and 1'.6 nitrogen.- Example 4.-Pr pamt on I t qld czsu iwized iA'mfiXtu'rebf 1j13"g1*ams"(().4 men primed aid and 128 grams (0.4: molyiofsulfurwasheated for 1% hours -at165 C.

The thiaidine' salt 'wasfprepared as described in Example 1,"'using 94.4"g'rams. (0.3 mol) basalfurizedoleic acidfiand '49.0'?'grams (0.3 molflof thialdine. A dark "red liquidwas' obtained'fwlii'ch upon analysis was found to contain 18.5%"s'ulfur and 2.5% nitrogen.

These four products "were then tested inithe laboratoryfor their inhibitingaction againsfithe corrosion "of lead in copper lead bearings} as shown'inthefollowlng'examples,

z E-wample. 5 1 v In this tes't'the additives'were'blendcdj' byivvei'ght' 'conc'entration''an.extractedv Continent oil of S-J'A. E} 201gradeandicompara tive' tests run on these blends, and "on a sample of "the unblended 011;'Thetestwas mfi uc' d as follows: a f f I 1 500 cc. of the oil was placedj'inaglass'. ox a-" tion tube 13.,incheslbhg'ahd"2%inches"" amet'er; 'fitted at the bottom .f'with' a; "$4; r inlet tube perforated to facilitate'airdistribu i tion. The oxidation tube was then immersed in a heating bath so that the oil temperature was maintained at 325 F. throughout the test. Two quarter sections of automotive bearings of copperlead alloy, of known' weight and having a total surface area of 25 sq. cms.', were attached to opposite sides of a stainless steel rod which was then immersed in the test oil and rotated at 600 R. thus providing sufiicient agitationo'f the oil during the test. -1Air .was then blown through-theoil at the rateof 2 cu. ft. per hour. At the end of each four-hour period, the hearings were removed, washed with naphtha, and weighted to determine the amount of loss by corrosion. The bearings werethenrepolished (to increase the severity of the test) revveighted' and then subjected to the test for additional four-hourfperiods in like manner. The resultsare' givenfin the following table as corrosion life, which indicates the number of hours;. required for the bearings to lose 100 mgs. in weight, determined Example 6 To confirm the results of this laboratory test, under actual operating conditions, a further test wa run, using a S. A. E. 30 extracted Coastal oil containing 1% of the thialdine methylcyclohexyl thiophosphate of Example 2 as crankcase lubricant in a Lauson engine. The operating conditions were 295 F. jacket temperature, 300 F. oil temperature, and 1800 R. P. M. at 1.5 indicated kilowatt load, and the duration of the test was 25 hours. At the end of the test the loss in weight of the copper-lead bearing was determined. A blank test was run for comparison, using the base oil alone. The results of the test are shown below.

Weight Loss per Bearing Oil From the preceding examples it will be evident that the thialdine salts of the present invention are eifective antioxidants for lubricating oils.

As previously stated, any of the alkyl homologs of thialdine may be employed although thialdine itself is preferred. The acid radical may be that of a long chain acid such as oleic, palmitic or stearic acid, or lower monoor dibasic acids such as butyric, adipic or sebacic acid may be used. Sulfur-containing acids are preferred in the carboxylic acid class, and these may be readily prepared, for example, by heating the acid with elemental sulfur or with a sulfur halide.

The additives may be blended in the oil in amounts of from about 0.02 to by weight, 0.5 to 2% being the preferred range. For load-bearing purposes quantities of 2 to may be used. For handling and storage, concentrates containing 15 to 50% or more may be prepared. These may be added to base stocks to give blends of the desired concentration.

In addition to the additives of this invention there may also be added to the oil other conventional 1 additives. including detergent types paddltives, such as metalsoaps,metalpetroleum sulfonatesmetal phenates, metal alcoholateametal alkyl phenol sulfides, and the like.. Examples of such additional additives; are barium .tert..-octyl phenol sulfide, calcium :tert.:-amyl phenol sulfide, cadmium or nickel oleat'es, calcium phenyl stearate, aluminum naphthenate, and zinc methylcyclohexyl thiophosphate.

The lubricating oilbase stocks used maybe straight mineral lubricating oils or distillates derived from any suitable or desired crudes, or, if desired, blended oils maybe employed. The oils may have been subjected to any conventional refining-treatment such as acid, alkali and/or clay treatment, or solvent extraction. 3 Synthetic oils such as those prepared by the polymerization of olefins or by the Fischer-Tropsch synthesis may alternatively be employed, alone, mixed, or in combination with mineral oils.

Further types of additives which may be present if desired include dyes, pour point depressants, heat thickened fatty oils, sulfurized fatty oils, organo-metallic compounds, sludge dispersers, thickeners, viscosity index improvers, oiliness agents, volatilized fats, waxes or oils, and colloidal solids such as graphite or zinc oxide, etc. Solvents and assisting agents such as esters, ketones, alcohols, aldehydes, and halogenated or nitrated hydrocarbons may also be employed where necessary or desirable.

Particularly suitable assisting agents are the Ca and higher alcohols (preferably C8 to C12) such as lauryl and stearyl alcohols, and the OX0 alcohols of corresponding chain length.

In addition to being employed in lubricants, the additives of the present invention may also be employed in other hydrocarbon products susceptible to oxidative breakdown. Among these maybe mentioned motor fuels, mineral oil base hydraulic fluids, torque converter fluids, cutting oils, flushing oils, turbine oils, transformer oils, industrial oils and process oils, natural and synthetic hydrocarbon rubbers, and the like. They may also be used in gear lubricants, greases, and in other products containing hydrocarbon oils as ingredients.

What is claimed is:

1. As a new composition of matter, the salt of a compound of the general formula R f S S R( JH 611-43.

wherein R. is a C1 to C10 alkyl radical, and a thiophosphoric acid in which at least one of the hydrogen atoms is replaced by a hydrocarbon radical containing in the range of 2 to 30 carbon atoms.

2. A composition as in claim 1 in which said thiophosphoric acid has the formula hydrocarbon radical having in the range of 2 to 20 carbon atoms. 

1. AS A NEW COMPOSITION OF MATTER, THE SALT OF A COMPOUND OF THE GENERAL FORMULA 